How to Make It
Preheat oven to 450°F. Cook chorizo in a 12-inch cast-iron skillet over medium-high, stirring occasionally, until browned, about 5 minutes. Transfer to a plate using a slotted spoon.
Season chicken with pepper and ¾ teaspoon salt. Add to skillet, skin side down, and cook until skin is browned and crisp, about 6 minutes. Transfer to plate with chorizo.
Add halved spring onion bottoms, red onion, garlic, and chorizo to skillet and stir to combine. Place chicken, skin side up, on top of mixture and transfer skillet to oven. Roast until a thermometer inserted in thickest part of thighs registers 165°F, about 15 minutes. Remove from oven.
Meanwhile, heat oil in a medium pot over medium-high. Add pasta and cook, stirring often, until browned, about 2 minutes. Stir in yellow onion and cook, stirring occasionally, until beginning to soften, about 3 minutes. Stir in rice, broth, and remaining ¼ teaspoon salt. Bring to a boil, reduce heat to medium-low, and simmer, covered, until rice is tender, about 15 minutes. Remove from heat and let stand, covered, for 3 minutes.
Top chicken with spring onion tops and serve with rice pilaf.